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  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>
  <script>
    /* alert('你好 JS...')
    prompt('请输入你的年龄')
    document.write('javascript 我来了')
    console.log('他 会魔法吧~') */

    /* let uname = prompt('请输入姓名')
    document.write(uname) */

    /* let name = prompt('请输入你的姓名')
    let age = prompt('请输入你的年龄')
    let gender = prompt('请输入你的性别')
    document.write(name, age, gender)
    console.log(name, age, gender)*/


    /* let i = 1
    var n = 2
    var n = 35
    console.log(n) */


    let r = prompt('请输入圆的半径')
    const PI = 3.14
    // console.log('半径为' + r + '的圆的面积为' + PI * r * r)
    console.log(`半径为${r}的圆的面积为${PI * r * r}`)



  </script>
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